With custom __dir__:

Help on class Enum in module enum:

Enum = <enum 'Enum'>

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Without custom __dir__:

Help on class Enum in module enum:

class Enum(builtins.object)
 |  Generic enumeration.
 |  
 |  Derive from this class to define new enumerations.
 |  
 |  Methods defined here:
 |  
 |  __eq__(self, other)
 |  
 |  __getnewargs__(self)
 |  
 |  __hash__(self)
 |  
 |  __repr__(self)
 |  
 |  __str__(self)
 |  
 |  ----------------------------------------------------------------------
 |  Static methods defined here:
 |  
 |  __new__(cls, value)
 |  
 |  ----------------------------------------------------------------------
 |  Data descriptors defined here:
 |  
 |  __dict__
 |      dictionary for instance variables (if defined)
 |  
 |  __weakref__
 |      list of weak references to the object (if defined)
 |  
 |  name
 |      Route attribute access on a class to __getattr__.
 |      
 |      This is a descriptor, used to define attributes that act differently when
 |      accessed through an instance and through a class.  Instance access remains
 |      normal, but access to an attribute through a class will be routed to the
 |      class's __getattr__ method; this is done by raising AttributeError.
 |  
 |  value
 |      Route attribute access on a class to __getattr__.
 |      
 |      This is a descriptor, used to define attributes that act differently when
 |      accessed through an instance and through a class.  Instance access remains
 |      normal, but access to an attribute through a class will be routed to the
 |      class's __getattr__ method; this is done by raising AttributeError.

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I'm thinking we should drop the custom __dir__.  help() is far more important than not seeing some things with dir().